252 DISEASES OF CATTLE, SHEEP, GOATS, ETC. 



REVIEW OF RECENT LITERATURE. 



At the Ninth International Congress of Veterinary Medicine, 

 held at The Hague in September, 1909, the subject of immunization 

 against tuberculosis received most interested attention, and the papers 

 which dealt with this question were actively discussed. Among the 

 opinions which were expressed during this discussion we quote from 

 Dr. A. Eber, of Leipsic ; Dr. J. F. Heymanns, of Ghent ; Dr. Klimmer, 

 of Dresden ; Dr. Vallee, of Alfort ; and Dr. Arloing, of Lyon. 



Dr. Eber stated that the following conclusions had been reached 

 by him after careful study of the entire question and after observing 

 the results of numerous preventive inoculations : 



The receptivity of young cattle to experimental infection by vir- 

 ulent tubercle bacilli may be materially diminished by previous inocu- 

 lation with the Koch bacillus, even of varied origin and virulence. 

 The immunity thus conferred is not absolute. The immunized cattle 

 will succumb from the effects of a sufficiently heavy dose of tubercu- 

 lous virus. 



The increase of resistance is not complete for some time (at least 

 three months) after inoculation, and has entirely disappeared at the 

 end of the first or second year. The degree and duration of the ex- 

 perimental immunity are influenced by the individual resistance, and 

 up to a certain point by the quality of the vaccine used. 



No experimental method permits one to foresee the manner in 

 which the vaccinated animals will comport themselves toward natural 

 or enzootic contagion. Practice alone must decide the value of im- 

 munization in the struggle against bovine tuberculosis. Tuberculin 

 does not positively disclose the existence of tuberculous centers upon 

 animals previously treated by injections of living tubercle bacilli. 

 Science has not yet granted us a method of inoculation which permits 

 effective struggle against tuberculosis in regions seriously infected. 



The new researches simply shed a light upon preventive inocu- 

 lation when combined with other prophylactic measures (killing ani- 

 mals affected with open tuberculosis, raising the calves on sterilized 

 milk, plowing pastures) during the struggle against tuberculosis. 



In practice one prefers methods of immunization which permit 

 annual reinoculation. Nevertheless, more exact researches must be 

 instituted for the purpose of determining if annual preventive inocu- 

 lation is sufficient in every case to confer satisfactory immunity. 



It is of great importance for the future to study further the in- 

 fluence of the mode of inoculation (intravenous, subcutaneous, diges- 

 tive) upon the quality and duration of the immunity acquired, keep- 

 ing constantly in mind at the same time the various doors of entrance 

 of natural infection (digestive or respiratory). 



Dr. Heymanns limited his report to a discussion of the method 

 which he discovered, and which consists in inserting into the animal 

 vaccinated the unattenuated tubercle bacilli inclosed within a dialyz- 

 ing membrane. 



Healthy animals thus vaccinated offer greater resistance to in- 

 fection, whether by inoculation or stabling, than the checks. Al- 

 though the duration and the degree of immunity are limited, the re- 



